1. Field of the Invention
The present invention relates to an apparatus for penetrating body tissue. More particularly, the present invention relates to a pneumoperitoneum needle having an inner needle fabricated from an electrically conductive material and an outer sheath fabricated from an electrically insulating material.
2. Description of the Related Art
Pneumoperitoneum needles have been used to insufflate the abdominal cavity to facilitate laparoscopic and endoscopic examination and surgery of body tissue. One type of pneumoperitoneum needle, commonly known as the Veress-type pneumoneedle, includes a spring loaded blunt stylet in a larger diameter hollow needle. Once the pneumoneedle penetrates the abdominal wall and enters a body cavity, the resistance against the end of the needle ceases and the spring pushes the blunt end of the stylet forward so that it extends beyond the sharp tip of the needle. Thus when the needle penetrates the body tissue the sharp tip of the needle is prevented from puncturing or lacerating intra-abdominal structures.
Another Veress-type pneumoneedle is described in U.S. Pat. No. 5,139,485 to Smith et al. The needle described has a sharpened outer needle and allows passage of a blunt inner needle within the outer needle. In addition, the needle contains a position indicator within the outer needle which indicates whether the needle is in a protective or non-protective position. An acoustical enhancement mechanism is described which amplifies the sound of the inner needle moving to the protective position.
The present invention, on the other hand, provides a new and cost effective apparatus and method for detecting penetration of the peritoneum or other body portions by a hollow needle.